The epidemic of type 2 diabetes (T2DM) that has affected the world's populations threatens to become this century's major public health problem. The enormous human and economic costs associated with the epidemic in the US (prevalence of ~25 million, incidence 1.9 million per year) are related primarily to the development of long-term complications including retinopathy, nephropathy, and neuropathy that cause more cases of blindness, renal failure, and amputations than any other disease. Cardiovascular disease (CVD) is increased 2-5 fold in T2DM and is the leading cause of premature death. High quality clinical trials have established the importance of lowering glycemia to reduce long-term complications. Progression of T2DM usually requires addition of a second agent to metformin, the accepted first line treatment. With the development of numerous new classes of glucose-lowering drugs, evidence to guide the choice of the second agent is lacking, prompting the proliferation of conflicting guidelines that acknowledge this deficiency. Moreover, while these agents are typically used for many years, data on long-term use are non-existent. Comparative effectiveness research is a high priority to improve public health and maximize cost-effectiveness in the treatment of T2DM. In addition, efforts to individualize T2DM therapy and determine whether selected therapies work better in some patients than others are needed, as are studies to understand differential effects of various therapies on metabolism over time. The Glycemia Reduction Approaches in Diabetes: A Comparative Effectiveness (GRADE) Study will address these questions in a randomized, pragmatic clinical trial in 6000 patients with recent-onset (<5 years duration) T2DM. GRADE will compare the metabolic effects of four common glucose-lowering medications, the sulfonylurea glimepiride, DPP-4 inhibitor sitagliptin, GLP-1 agonist liraglutide, and basal insulin glargine, added to metformin, over a clinically meaningful duration, with a mean exposure of 4.5 (3-6) years. The primary outcome is the time to primary metabolic failure (hemoglobin A1c (A1C)>7%, subsequently confirmed).Other outcomes include mean A1C; time to a secondary metabolic outcome of A1C>7.5%, confirmed, after which basal insulin rescue therapy will be added; and adverse effects such as weight gain and hypoglycemia, effects on selected microvascular disease and CVD risk factors, tolerability and quality-of-life, and cost and cost-effectiveness. We will also examine the phenotypic characteristics and pathophysiologic factors associated with metabolic response to and/or failure of the drug combinations.